It is, thats what age of consent means. And in most states, the age of consent is 16-17. In those relevant states, any 16 year old person can freely consent to have sex with anyone else who is at least the age of consent or older. This is different than and is often confused with Romeo and Juliet laws where minors can legally have sex with other minors or people within a close enough age range. Age of consent is not that. it is plainly the age which a person can consent to sex.